华北地区夏玉米临界氮稀释曲线和氮营养指数研究

为了验证玉米临界氮稀释曲线在我国华北地区的适用性，探讨以氮营养指数评价玉米氮营养状况的可行性，以郑单958为材料，设置5个氮肥处理(0、60、120、180和240 kg N hm^-2)，利用2年定位试验数据研究了夏玉米临界氮稀释曲线和氮营养指数。结果表明，一定范围内随着施氮量增加，地上部生物量(W)显著增长。玉米各生育时期不同氮肥处理的生物量和氮浓度数据可经统计分析分为限氮和非限氮两组，据此计算各生育时期临界氮浓度(N_c)并建立了夏玉米临界氮稀释曲线模型(N_c = 34.914W^-0.4134)，模型参数与已有报道具有较好的相似性。根据模型推算的氮营养指数与相对氮累积量、相对地上部生物量和相对产量均具显著相关性。因此，利用临界氮稀释曲线和氮营养指数可以预测华北地区夏玉米植株临界氮含量和表征植株氮营养状况。

Critical Nitrogen Dilution Curve and Nitrogen Nutrition Index for Summer Maize in North China Plain

In order to verify the applicability of critical nitrogen (N) dilution curve for summer maize in North China Plain, and the feasibility of N nutrition index (NNI) in evaluating N nutrition status of maize plant, a 2-year experiment with five N-fertilizer treatments (0, 60, 120, 180, and 240 kg Nha^-1) was conducted using the cultivar Zhengdan 958. The results showed that the above ground biomass (W) increased significantly with increasing N-fertilizer application within a certain range. The data of above ground biomass and corresponding N concentration for each sampling stage were divided into N limited group and N non-limited group based on the statistical results, then the critical N concentration (N_c) was calculated and the critical N dilution curve model (N_c=34.914W^–0.4134) for summer maize was established, and the model parameters had a good similarity to these reported. NNI calculated based on the critical N dilution curve model had a significant correlation with relative N uptake amount, or relative above ground biomass or relative yield. Therefore, critical N dilution curve and NNI can be used to predict plant N_c and characterize plant N status in summer maize in North China Plain.